Researchers believe a coral reef collapse is looming

Pacific reefs had some bad millennia due to wild El Niños; bad sign for today.

If, as the song goes, you always hurt the one you love, humans must really love coral reefs. Reefs seem to be under siege from all sides. Between overfishing, nutrient pollution, climate warming, and ocean acidification, it’s no wonder marine biologists express so much concern for the future. Not all research has yielded doom and gloom, of course. Some species have shown the ability to deal with acidification or to adapt over a few generations; some high-latitude reefs limited by cold waters could see growth. But, on balance, the outlook is still decidedly bleak.

In the ongoing quest to see into the crystal ball a little more clearly, one route is to study how climate has impacted coral reefs in the past. A new study published in Science finds that climatic variability during the Holocene—the period since the end of the last ice age—strongly affected reefs in the Pacific. And the researchers believe it’s a preview of what’s to come.

The group studied reef sediment cores from three locations off the southern coast of Panama. The sites were chosen for their differing relationship with the upwelling in the Bay of Panama—where deep water rises to the surface. One location is smack in the middle of the upwelling zone, another is on the edge, and the third is outside it. The water that seasonally rises from the deep ocean is more acidic than surface water because CO2 has accumulated during its long journey along the seafloor.

That seasonal acidity is a source of stress for the coral reefs there, but so are the warm ocean temperatures in the eastern Pacific that come with El Niños. When the water is too warm, corals can “bleach”, expelling the photosynthetic symbionts that live inside them. If the corals don’t recover quickly, algae can take over. This reduces the diversity and structure of the reef to a carpet of green.

The sediment cores were dated using carbon-14 as well as a uranium-thorium method commonly used for corals, and the researchers noted how the mix of species changed through time. In each core, there was a thin layer where very little coral growth had taken place. And the corals that were present were in pretty poor shape.

The dating revealed this thin layer actually accounted for about 2,500 years, beginning around 4,000 years ago. For some reason, the coral communities had collapsed for more than two millennia before resuming growth.

Reefs elsewhere in the Pacific—near Costa Rica, Australia, and Japan—went through similar growth “hiatuses” at nearly the same time. Previously, each had been chalked up as one-off, regional events. But now researchers argue they seem to be part of the same, larger story.

El Niño-Southern Oscillation (ENSO)

The El Niño-Southern Oscillation (ENSO) is a change in the surface ocean temperatures that occurs in the tropical Pacific Ocean. During the El Niño phase, surface waters are warmer than average, while they are cooler in the La Niña phase. Because the area of the ocean that is affected by the ENSO is so large, the impact of the ENSO is felt globally, and is a major contributor to short-term climate variability. Currently, we do not have a strong understanding of what drives the ENSO.

A little over 4,000 years ago, the El Niño Southern Oscillation (ENSO) began behaving oddly, with El Niños occurring more frequently and much more strongly than usual. That was amplified by increased variability in the position of the Intertropical Convergence Zone—the boundary that separates the atmospheric circulation in the Northern and Southern Hemispheres and drives the equatorial monsoons.

There are still some open questions, but since stronger El Niños (and more frequent heat stress events) are expected as climate warms, the researchers believe that this period tells us something about how Pacific reefs will respond. They don’t appear to be as resilient to climatic variability as we might hope. The researchers write, “Global climate change is probably driving eastern Pacific coral reefs toward another regional collapse.”

They do, however, end on a positive note. Since the reefs were able to recover after 2,500 years of collapse, perhaps they’ll similarly bounce back once we get around to dealing with our greenhouse emissions. Of course, temperature isn’t the only problem facing reefs today, so, as the saying goes, past performance is no guarantee of future results.

When the water is too warm, corals can “bleach”, expelling the photosynthetic symbionts that live inside them. If the corals don’t recover quickly, algae can take over. This reduces the diversity and structure of the reef to a carpet of green.

Cool -- I always just assumed that when coral reefs "bleached" it was because of the affect of the sun on the coral. Learn something new everyday and all that.

When the water is too warm, corals can “bleach”, expelling the photosynthetic symbionts that live inside them. If the corals don’t recover quickly, algae can take over. This reduces the diversity and structure of the reef to a carpet of green.

Cool -- I always just assumed that when coral reefs "bleached" it was because of the affect of the sun on the coral. Learn something new everyday and all that.

You aren't the first to be confused by that term. The symbionts (xoozanthellae) give color to the corals, so the reefs goes white when they get kicked out.

Unnecessary artsy impression, but the picture reminds me of an abstract version of Michael Angelo's pieces. The coral looks like small disfigured humans that have been re purposed (yeah I have no clue where I thought of that either)

Does this study only deal with warm water/tropical reefs? The cold water and deep sea reefs are less studied so far but seem to house a much greater diversity of species... many of whom have incredibly odd mutations, even more so that the panoply of weirdness that is a tropical coral reef.

Additionally, the cold water reefs, particularly the Antarctic ones, seem to provide a much larger portion of the base of the food chain. If they are not being similarly affected, the strange and as-yet-unexplained plankton bloom happening below the antarctic ice is some cause for hope: that the tropical reefs may collapse, but the oceanic food chain may stay intact.

Does this study only deal with warm water/tropical reefs? The cold water and deep sea reefs are less studied so far but seem to house a much greater diversity of species... many of whom have incredibly odd mutations, even more so that the panoply of weirdness that is a tropical coral reef.

Additionally, the cold water reefs, particularly the Antarctic ones, seem to provide a much larger portion of the base of the food chain. If they are not being similarly affected, the strange and as-yet-unexplained plankton bloom happening below the antarctic ice is some cause for hope: that the tropical reefs may collapse, but the oceanic food chain may stay intact.

That ice is melting at an accelerating rate, I wouldn't count on that as a backup plan.

Zarkonite wrote: That ice is melting at an accelerating rate, I wouldn't count on that as a backup plan.

Indeed. We may already have passed the point of no return to the current Ice Age, which became possible with the closing of the Centreal American Seaway ~5mya but didn't really result in glaciation until ~3.5mya when the resulting Global Oceanic Conveyor moderated sufficiently to allow Arctic sea ice to accumulate.

Its been estimated the Antarctic ice sheet began to accumulate when atmospheric C02 concentrations, previoulsy maintained by volcanism associated with continental drift, slowly dropped to beneath ~450ppm.Source: The 8 Minute Epoch 65 million Years with James Hansen http://www.youtube.com/watch?v=TSexmRu3 ... re=related

We're currently at 385ppm and increasing at ~2ppm/year the past decade. Back in the 60's it was about 0.7ppm/year. Carbon dioxide is not the only greenhouse gas. NOAA calculates the Annual Greenhouse Gas Index every year, which takes into account the heating effects of other gases that are emitted from human activities (e.g., methane, nitrous oxide, and chemicals called chlorofluorocarbons). When those gases are also considered, the global atmosphere reached a CO2 equivalent concentration of 400 ppm in 1985; and 450 ppm in 2003. Atmospheric CO2 levels are currently higher than they have been at any time during the last 800,000 years. Watch a NOAA Earth System Research Laboratory animation of carbon dioxide levels for the past 800,000 years on YouTube athttp://www.youtube.com/watch?v=SXHDwdd7Tf8Source:http://researchmatters.noaa.gov/news/Pages/arcticCO2.aspx

All the focus on green is turning the world black. We know it is better to teach children, people, <i>how</i> rather than what to think, yet this "green" push is increasingly becoming a socio-political religion than anything else, regardless of what actual truth there is behind it. It's being over-marketed and commercialized to the point that anything that is labeled "green", "natural", "organic", what have you, has no relation to anything but an increase in price or subscription to a particular ideology. The risk is that people will (are) become so sick and tired of being preached to, misled, and scammed, that the integrity of the generic concept is buried and destroyed. However, perhaps it is this, the green-movement, that might be humanity's greatest failure that will serve also as it's greatest learning experience. No less do we, as a species, need to fall before we pick ourselves up, to we as individuals.

I wish these articles would say what 'bleaching' means, why it's bad, and what the consequences are. It might be good to stop assuming everyone already knows that.

I'm a lay science nerd and I don't even know what that means off the top of my head and I can quote black hole info chapter and verse. I'm sure I'm not alone.

From the article:

Quote:

When the water is too warm, corals can “bleach”, expelling the photosynthetic symbionts that live inside them. If the corals don’t recover quickly, algae can take over. This reduces the diversity and structure of the reef to a carpet of green.

All the focus on green is turning the world black. We know it is better to teach children, people, <i>how</i> rather than what to think, yet this "green" push is increasingly becoming a socio-political religion than anything else, regardless of what actual truth there is behind it. It's being over-marketed and commercialized to the point that anything that is labeled "green", "natural", "organic", what have you, has no relation to anything but an increase in price. The risk is that people will (are) become so sick and tired of being preached to, misled, and scammed, they integrity of the wider concept is buried and destroyed. However, perhaps it is this, the green-movement, that might be humanity's greatest failure that will serve also as it's greatest learning experience. No less do we, as a species, need to fall before we pick ourselves up, to we as individuals.

What does this have to do with the article?

The only "green" in the article is the algae that tend to take over if the coral organisms die.

I think that you need to either read the article before posting, or possibly need to work on your reading comprehension.

If that's the only "green" ideology you see in the article, then maybe you need to take a step back, and examine it within larger context.

Pointing out that collapsing food chains might have adverse consequences is "green"?

No, but obsessing over it, prioritizing it reflexively above the many other concerns facing civilization, or allowing it to color one's worldview to the minimization or exclusion of such other issues would be. Those who look through green lenses fail to see all the other colors in the world--except maybe red, but I digress.

Note that I'm not accusing the article itself of any such thing. It's a good, well-written article. It is however on the weighted side of the scale of Ars' scientific coverage, where green issues are given a very large focus. I realize that much of this is due to the interests of editors and writers, which also affect Ars' similar leanings toward specific physics areas, and is not some deliberate agenda. People notice and write about what interests them. This is understandable.

People notice and write about what interests them. This is understandable.

People sometimes also write about what interests their readers as well. And there is a lot of interest here about "green" issues. As well there should be, for reasons outlined above. Some are not so concerned with the Ice Age's impending end; as no less an authority than ExxonMobil CEO Rex Tillerson recently opined in a speach at the Council on Foreign Relations:

Quote:

...fears about climate change, drilling, and energy dependence are overblown. In a speech Wednesday, Tillerson acknowledged that burning of fossil fuels is warming the planet, but said society will be able to adapt. Tillerson blamed a public that is "illiterate" in science and math, a "lazy" press, and advocacy groups that "manufacture fear" for energy misconceptions

While Mr. Tillerson is no doubt correct about there being a large amount of ill-informed advocacy group "manufactured fear", that doesn't at all mean there is nothing to be fearful of. I repeat: the current Ice Age began about 3.5 million years ago. It is the only age homids of any sort -- not just Homo (alleged) Sapiens have ever known. The notion that "society will be able to adapt", while comforting, is one based upon not a shred of evidence, historical, anthropological, paleantological, or otherwise.

Yes, the richest few percent of society -- them with the energy to do so -- will probably survive. As for the rest: Hey! They don't call it "social darwinism" for nothing!

The International Coral Reef Symposium (http://www.icrs2012.com/) is being held in Cairns, Australia, from 9 to 13 July (next week). There are a great many interesting presentations, including many dealing with bleaching and the causes thereof. The book of abstracts is on their website.

When the water is too warm, corals can “bleach”, expelling the photosynthetic symbionts that live inside them. If the corals don’t recover quickly, algae can take over. This reduces the diversity and structure of the reef to a carpet of green.

I believe that earth has a balancing system whereby any damages that happens will repair itself in a few million or so. We humans are actually tick which has a parasitic and/or symbiotic relation with our planet. After all humans have gone (either the "At childhoods end" ending or other apocalyptic ends) earth will begin to renew itself and by 1,000,000 years no traces of humanity will be seen.

Pointing out that collapsing food chains might have adverse consequences is "green"?

No, but obsessing over it, prioritizing it reflexively above the many other concerns facing civilization, or allowing it to color one's worldview to the minimization or exclusion of such other issues would be.

I for one would be really interested in hearing your list of issues that need to be given higher priority than collapsing food chains.

Pointing out that collapsing food chains might have adverse consequences is "green"?

No, but obsessing over it, prioritizing it reflexively above the many other concerns facing civilization, or allowing it to color one's worldview to the minimization or exclusion of such other issues would be.

I for one would be really interested in hearing your list of issues that need to be given higher priority than collapsing food chains.

Unnecessary artsy impression, but the picture reminds me of an abstract version of Michael Angelo's pieces. The coral looks like small disfigured humans that have been re purposed (yeah I have no clue where I thought of that either)

I don't know why, but I saw the same thing when I scrolled over this article. Only once I read the title did I realize it was about coral.

I believe that earth has a balancing system whereby any damages that happens will repair itself in a few million or so. We humans are actually tick which has a parasitic and/or symbiotic relation with our planet. After all humans have gone (either the "At childhoods end" ending or other apocalyptic ends) earth will begin to renew itself and by 1,000,000 years no traces of humanity will be seen.

How bout the next intelligent life form dig our human fossils and human artifacts? They can see us through their museums?

I for one would be really interested in hearing your list of issues that need to be given higher priority than collapsing food chains.

Is the claim that changes to coral reefs are in the medium future - say the next 50 years - likely to have significant impacts on the global food supply situation? I guess its possible, but it seems a bit unlikely.

I should be very sorry to see coral reefs greatly diminished for quite different reasons, but would like to have some quantified account of the effect on global food supply before accepting this one.

I'm also interested in how much ocean temperatures are rising, have risen, and what the temperature danger level is. Anyone know?

All the focus on green is turning the world black. We know it is better to teach children, people, <i>how</i> rather than what to think, yet this "green" push is increasingly becoming a socio-political religion than anything else, regardless of what actual truth there is behind it. It's being over-marketed and commercialized to the point that anything that is labeled "green", "natural", "organic", what have you, has no relation to anything but an increase in price or subscription to a particular ideology. The risk is that people will (are) become so sick and tired of being preached to, misled, and scammed, that the integrity of the generic concept is buried and destroyed. However, perhaps it is this, the green-movement, that might be humanity's greatest failure that will serve also as it's greatest learning experience. No less do we, as a species, need to fall before we pick ourselves up, to we as individuals.

Actually, there isn't much integrity with the generic concept here. Past something like 400ppm of CO2, it stops acting as a greenhouse gas. Really, all we have to do in order to stop CO2 from going up is recycle more, use less paper, and therefore cut down less trees. They will take up the slack.

Plant some flowers around your home as well, they will take up some of the slack as well.

Now, as to other greenhouse gases, those are something that we have to worry about.... but the fact is that most of them have been phased out of usage even in China, so they are not a big worry.

Actually, there isn't much integrity with the generic concept here. Past something like 400ppm of CO2, it stops acting as a greenhouse gas.

Nope. See especially comment #4. We're nowhere close to saturating the GHG effect.

Quote:

Really, all we have to do in order to stop CO2 from going up is recycle more, use less paper, and therefore cut down less trees. They will take up the slack.

No. Human emissions are 2x the rise in CO2 annually. This means that all of nature acting as a sink is only enough to compensate for half the CO2 we emit. There isn't enough land to cover with plants to take up the rest of it. Deforestation is definitely a contributor to the CO2 increase (in several ways), but halting it entirely and even reversing it would not stop or reverse the increase in atmospheric CO2.

Quote:

Now, as to other greenhouse gases, those are something that we have to worry about.... but the fact is that most of them have been phased out of usage even in China, so they are not a big worry.

Pointing out that collapsing food chains might have adverse consequences is "green"?

No, but obsessing over it, prioritizing it reflexively above the many other concerns facing civilization, or allowing it to color one's worldview to the minimization or exclusion of such other issues would be.

I for one would be really interested in hearing your list of issues that need to be given higher priority than collapsing food chains.

Civilizations are at least as intricate and delicate as climatic systems and food chains. Stress them in the wrong way and they break, sometimes taking a few decades and sometimes taking a thousand years to recover to previous levels of technological and philosophical advancement. If a regional ocean food chain is disrupted due to loss of coral reef habitats, this would be unfortunate--but significant civilizations have access to other food sources, and could develop more if needed. There are many economic, political, and cultural concerns both internal and external which impose more of an existential threat (or technological and cultural retardation threat) to civilizations such as those of the U.S. and Europe than would the collapse of certain fisheries due to reef habitat loss. Some civilizations would be far more impacted by regional reef ecosystem collapses than the larger Western ones, but I can't say that they're my concern.

Clearly, other people may have different concerns and priorities. My primary concern and priority is the advancement of civilization along technologically progressive and culturally liberal lines. First you have to define what it is you value and wish to promote before you can adequately discuss issues. Too many on the environmental left just have some sort of unreasoned desire for arbitrary stasis, which they can't define and can express only reflexively. Of course a collapsing regional food chain is bad in absolute terms--but how bad relative to and in proportion to what, from the perspective of whom, and what are the costs:benefits of possible actions? Only when we take wider concerns into account, and when we recognize that we come from particular perspectives with certain agendas and don't live in a world of abstract absolutes, can we really discuss the issues and how to prioritize them.

Pointing out that collapsing food chains might have adverse consequences is "green"?

No, but obsessing over it, prioritizing it reflexively above the many other concerns facing civilization, or allowing it to color one's worldview to the minimization or exclusion of such other issues would be.

I for one would be really interested in hearing your list of issues that need to be given higher priority than collapsing food chains.

Civilizations are at least as intricate and delicate as climatic systems and food chains. Stress them in the wrong way and they break, sometimes taking a few decades and sometimes taking a thousand years to recover to previous levels of technological and philosophical advancement. If a regional ocean food chain is disrupted due to loss of coral reef habitats, this would be unfortunate--but significant civilizations have access to other food sources, and could develop more if needed. There are many economic, political, and cultural concerns both internal and external which impose more of an existential threat (or technological and cultural retardation threat) to civilizations such as those of the U.S. and Europe than would the collapse of certain fisheries due to reef habitat loss. Some civilizations would be far more impacted by regional reef ecosystem collapses than the larger Western ones, but I can't say that they're my concern.

Clearly, other people may have different concerns and priorities. My primary concern and priority is the advancement of civilization along technologically progressive and culturally liberal lines. First you have to define what it is you value and wish to promote before you can adequately discuss issues. Too many on the environmental left just have some sort of unreasoned desire for arbitrary stasis, which they can't define and can express only reflexively. Of course a collapsing regional food chain is bad in absolute terms--but how bad relative to and in proportion to what, from the perspective of whom, and what are the costs:benefits of possible actions? Only when we take wider concerns into account, and when we recognize that we come from particular perspectives with certain agendas and don't live in a world of abstract absolutes, can we really discuss the issues and how to prioritize them.